Visual features of the oral region in Polish sibilants produced by children with various sibilance patterns

This paper analyzes the 2D and 3D visual features of Polish sibilants /s/ and /ʂ/ articulated by 189 children aged 4;11-8;0. Our goal was to (1) analyze differences in shape image features of delineated articulators (lips, tongue, and mouth - lips and space between them) in selected sibilants and (2) investigate a relationship between visual parameters and sibilance pattern (the character of a gap between teeth that allows the articulation of sibilant sounds). We employed 2D and 3D shape image features and linear mixed-effect models. The results proved significant differences between sibilants in 2D and 3D visual features of lips and mouth. Different sibilance patterns considered in the study also significantly impacted visual parameters distribution. Our findings indicate the potential of video data in computer-aided speech diagnosis.